JUPITER, Fla. — St. Louis Cardinals ace Adam Wainwright will have Tommy John surgery on his right elbow and miss the entire season.

Cardinals general manager John Mozeliak confirmed the news Thursday from spring training camp. He said he learned the severity of the injury Wednesday night after the 29-year-old pitcher sought a second opinion from Dr. Lewis Yocum in Los Angeles. A surgery date is not set.

"It's not a real surprise to us but certainly a disappointment," Mozeliak said. "As we look to the future now we certainly believe we still have a strong starting rotation. Now we're going to have to look to try to fill it in terms of a fifth spot."

Wainwright, who won 20 games last year and was runner-up for the NL Cy Young Award, felt arm stiffness after Monday's throwing session. He had experienced soreness toward the end of last season and didn't pitch in September. He had minor arm issues in 1998 and 2004.

His loss leaves the team with a big hole in a starting rotation that for now includes Chris Carpenter, Kyle Lohse, Jaime Garcia and Jake Westbrook.

"That's a big guy to miss," Lohse said. "We still got to go out there and play. Nobody is going to feel sorry for us. We still have to go out there and do our jobs."

The Cardinals entered spring training with a rotation that Mozeliak said he would stack up against any in baseball.

"You're losing an ace," Mozeliak said. "It's not something you can replace overnight. I would also say we have four quality pitchers. It's not exactly like we have no bullets left."

Manager Tony La Russa said Wednesday, before learning the extent of the injury, that he didn't expect the Cardinals to try to replace Wainwright through a trade or free agent signing of someone like Kevin Millwood or possibly Pedro Martinez.

But that could change.

"You follow camps and see if something develops where it's a good fit," La Russa said. "But right now it's not a good fit because were going to cover it from within. We'll pay attention though, that's part of what you do in spring training. We have scouts all over and we'll watch box scores."

La Russa has six or seven pitchers in camp who will have the opportunity to join the rotation.

"Guys are assigned at least a couple appearances over the first eight to 10 games and then a lot of those decisions make themselves," La Russa said.

The list is headed by reliever Kyle McClellan and includes P.J. Walters, Lance Lynn, Adam Ottavino, Ian Snell, Brian Tallet and Brandon Dickson. McClellan and Tallet are penciled in to join the Cardinals bullpen. Walters, Lynn, Ottavino and Dickson helped comprise the Triple-A Memphis staff for most of last season.

La Russa sees plenty of work for the candidates during the early spring training games.

"Early it's not a problem," he said. "Even if you want to give a guy a look or something the squeeze comes after you've gone through the group twice, when you start really getting the guys (work) that are on the club. So we'll see where we are."

Tommy John surgery reconstructs the ulnar collateral ligament, replacing it with a tendon from elsewhere in the body. The procedure requires months of recovery. It is named after the pitcher who in 1974 became the first professional athlete to successfully have had the operation.

Mozeliak said spoke to Wainwright late Wednesday.

"Obviously he's down," Mozeliak said. "But he certainly understands what's at stake and he's disappointed but I think he's also relieved to know what the next step looks like."

The 6-foot-7 Wainwright went 20-11 with a 2.42 ERA last season, finishing behind Philadelphia's Roy Halladay in Cy Young balloting while making his first All-Star team. His 2.93 ERA since 2007 trails only Halladay, and no NL pitcher threw more than Wainwright's 463 1-3 innings during the past two seasons.

In 2009, Wainwright led the NL in wins (19), innings (233) and starts (34), winning a Gold Glove while finishing third in Cy Young voting.